This third instalment in the Chronicles of Riddick series finds Vin Diesel fighting alien-like beasties on a desolate, lonely planet before engaging in a game of cat-and-mouse with visiting bounty hunters. At first it's serviceable space-lizard fare, with Diesel doing his usual camp, gruff-and-buff, bump-and-grind routine to generic ends. The arrival of company ups the character-ante, with Katee Sackhoff enjoying herself as the lethal warrior queen who proudly declares: "I don't fuck guys, but I do fuck them up." Shame, then, that the script promptly shoots itself in the equal-ops foot with some repellently ill-judged rapey "humour", promptly undermining any residual goodwill. This sour taste taints the entire third act, allowing the spectre of boredom to descend like a pitch-black cloud of despond.